Effects of operational conditions on hollow fiber nanofiltration for micropollutant removal from wastewater effluent

To remove organic micropollutants from wastewater effluent, hollow fiber nanofiltration (HFNF) is a promising solution based on lab scale work with mostly synthetic solutions. In this study, we investigate the application of commercially available HFNF membranes on a pilot scale (1 m³ h⁻¹) for real wastewater effluent treatment. The effects of scale, recovery, flux, crossflow velocity and staging are presented, with a focus on their impact on the retention of ions and organic micropollutants (OMPs), while considering the energy consumption. It is shown that the retention measured for OMPs is substantially higher on the benchtop scale compared to the pilot scale. The most effective strategy to improve retention on a pilot scale is to decrease the recovery or increase the flux. The energy consumption shows that crossflow velocity has a major impact on energy consumption, whereas flux and recovery play a smaller role. Furthermore, Christmas Tree (CT) configurations have an energy consumption that is significantly lower than Feed & Bleed (FB) modes, ranging from 0.11-0.14 kW h m⁻³ for CT mode and around 0.29 kW h m⁻³ for FB mode at a crossflow velocity of 0.4 m s⁻¹. Overall, the success of the HFNF membrane for OMP removal from wastewater depends on the targeted OMPs, combined with the way the OMPs in the concentrate are removed.